According to Miguel Rodríguez Llopis, in his book General History of Murcia which has been published posthumously; in the middle of the eighteenth century the average height of people in Murcia was 1.6m. Children from rich families averaged heights of 1.65m whereas those from working families only averaged 1.58m.
Rodríguez explains that these differences were due to the poorer diet and the greater incidence of diseases like typhoid and malaria amongst the working classes. There were even differences between people of the same class according to whether they lived in the countryside or in a city or town.
By 1880, at the height of the industrial and commercial revolution, the average height of Murcians had increased to 1.63m and the difference between those who lived in the country and those in towns was reduced to 2cms.
Today the average height of Spaniards is 1.68m (1.74m for men and 1.64m for women). However, it is noticeable that a lot of the young people are taller than their parents so maybe that will have changed by the next generation.
So it's not just our skin colour, the colour of our hair and eyes and the way we dress that gives us away; it is the fact that we are so tall that marks us out as Brits.
Mind you even we don't come near to the Dutch who average 1.79m (1.83m for men) which is a centimetre more than the Swedes and the Norwegians.